Unveiling the Trigonometric Relationship: Demystifying tan as a Function of sin and cos

Getting Started

Trigonometry is a branch of mathematics that deals with the relationships between the angles and sides of triangles. One of the basic trigonometric functions is the tangent, often abbreviated as tan. The tangent can be defined and understood in terms of the other two primary trigonometric functions, sine (sin) and cosine (cos). In this article, we will explore the relationship between the tangent, sine, and cosine functions and how they are related.

The Tangent Function

The tangent function, denoted as tan(θ), relates the length of the side opposite an angle in a right triangle to the length of the adjacent side. Mathematically, it can be defined as

tan(θ) = sin(θ) / cos(θ)

Where θ is the angle in question. As you can see, the tangent is the ratio of the sine of the angle to the cosine of the angle. This relationship is fundamental to trigonometry and has numerous applications in various scientific fields, including physics, engineering, and astronomy.

The sine function

The sine function, denoted sin(θ), also represents a ratio within a right triangle. Specifically, it relates the length of the side opposite an angle to the length of the hypotenuse, which is the longest side of the triangle. Mathematically, it can be expressed as

sin(θ) = opposite / hypotenuse

The sine function is periodic, oscillating between -1 and 1 as the angle θ changes. It is a fundamental trigonometric function used in various scientific and mathematical fields such as wave analysis, signal processing, and geometry.

The Cosine Function

The cosine function, denoted as cos(θ), is another trigonometric function that relates the ratio of the length of the side adjacent to an angle to the length of the hypotenuse in a right triangle. Mathematically, it can be written as

cos(θ) = side / hypotenuse
Similar to the sine function, the cosine function is periodic, oscillating between -1 and 1 as the angle θ changes. It is widely used in several scientific disciplines, including physics, engineering, and signal processing. The cosine function is particularly relevant in situations involving oscillatory motion and periodic phenomena.

The relationship between tan, sin, and cos

From the definitions of the tangent, sine, and cosine functions, we can derive the relationship between them. By substituting the definitions of sin(θ) and cos(θ) into the tangent function, we obtain

tan(θ) = sin(θ) / cos(θ) = (opposite / hypotenuse) / (adjacent / hypotenuse) = opposite / adjacent

As we can see, the tangent of an angle is equal to the ratio of the length of the side opposite the angle to the length of the side adjacent to the angle. This relationship provides a useful link between the three basic trigonometric functions, allowing us to express one in terms of the other two.
It is important to note that the tangent function is undefined when the cosine of an angle is zero. This occurs when the angle is 90 degrees or any multiple of 90 degrees. At these points, the tangent function has vertical asymptotes and its value approaches positive or negative infinity.

Applications of tan, sin, and cos

The tangent, sine, and cosine functions have a wide range of applications in various scientific disciplines. Here are a few examples:

  • Engineering: Trigonometry is used extensively in engineering fields such as structural analysis, electrical engineering, and mechanical engineering. These functions are critical for solving problems involving forces, vibrations, and electrical circuits.
  • Physics: Trigonometry plays an important role in physics, especially in areas such as classical mechanics, waves, optics, and electromagnetism. Functions are used to describe and analyze the behavior of waves, oscillations, and rotational motion.
  • Astronomy: Trigonometry is essential in astronomy for calculating distances, angles, and positions of celestial objects. The functions sin, cos, and tan are used to determine the apparent positions and motions of celestial bodies, as well as to study the geometry of celestial phenomena.
  • Navigation: Trigonometry is essential for navigation, both on land and at sea. Sailors and pilots use these functions to calculate distances, angles, and bearings to determine their position and navigate accurately.
  • Computer Graphics: Trigonometric functions are used extensively in computer graphics and animation to create realistic and visually appealing images. They are used to calculate angles, rotations, and positions of objects in three-dimensional space.

These are just a few examples of the many applications of the tangent, sine, and cosine functions. Their wide range of uses underscores the importance of understanding their definitions and relationships.


In summary, the tangent function can be expressed in terms of the sine and cosine functions as tan(θ) = sin(θ) / cos(θ). Trigonometry is a powerful mathematical tool that is used in a variety of scientific fields. Understanding the relationships between the tangent, sine, and cosine functions is critical to solving trigonometric problems and their practical applications in fields such as engineering, physics, astronomy, navigation, and computer graphics. By mastering these concepts, you will be able to solve a wide range of problems involving angles and triangles.


What is tan in terms of sin and cos?

Tan, short for tangent, is a trigonometric function defined as the ratio of the sine of an angle to the cosine of the same angle. In mathematical terms, tan(x) = sin(x) / cos(x), where x represents the angle.

How is tan related to sin and cos?

Tan is related to sin and cos through a simple mathematical relationship. It can be expressed as the ratio of sin(x) to cos(x), where x is the angle. Mathematically, tan(x) = sin(x) / cos(x).

What is the range of values for tan?

The range of values for tan is infinite. However, it has certain restrictions due to periodicity. The function repeats itself every π radians or 180 degrees. Therefore, tan(x) can take on any real value except when the angle x is an odd multiple of π/2 radians or 90 degrees, where the function is undefined.

How is tan calculated using sin and cos?

To calculate tan(x) using sin and cos, you divide the value of sin(x) by cos(x). For example, if sin(x) equals 0.8 and cos(x) equals 0.6, then tan(x) would be 0.8 divided by 0.6, which equals approximately 1.33.

Can tan be expressed solely in terms of sin or cos?

Yes, tan can be expressed solely in terms of sin or cos. By rearranging the trigonometric identity tan(x) = sin(x) / cos(x), we can also express it as tan(x) = 1 / cos(x) / 1 / sin(x). This allows us to represent tan(x) using only sin(x) or cos(x) alone.